This Stern Defense AR-15 Magazine Well Adapter will convert your standard mil spec AR 15, M4, M16 lower assembly to use 9mm Glock Magazines! The MAG-AD series adapters install in seconds. Boasting a last round hold open feature making them a breakthrough product and a must-have for law enforcement and civilian gun enthusiasts alike. The Stern MAG-AD series adapters are made of aircraft grade aluminum, lightweight with ergonomic design. Note: These adapters require the use of a 9mm barrel, "depending on chosen caliber" and a Glock cut bolt. FeaturesConstructed from 6061 T6 aircraft grade aluminum4140 NiB coated feed rampHard coat anodized type 3Sturdy ConstructionErgonomic mag releaseWorks with any mil spec ar15 lower receiverAll gun components besides the Bolt and Barrel remain stock DISCLAIMER: This product is not manufactured, authorized, endorsed, or warranted by GLOCK. GLOCK does not warrant or represent that this product is compatible with GLOCK pistols.